by Mike Chappell, USA TODAY Sports

by Mike Chappell, USA TODAY Sports

INDIANAPOLIS - The eerie silence of seeing a fallen teammate on the practice field has given way to a stark reality: The Indianapolis Colts will be without running back Vick Ballard for the rest of the season.

A Thursday night MRI on Ballard's right knee revealed he tore the anterior cruciate ligament during non-contact drills earlier in the day.

Friday, the team placed their leading rusher on the season-ending injured reserve list and filled his spot on the active roster by elevating rookie Kerwynn Williams from the practice squad. Ballard will require surgery.

Donald Brown feared the worst when he saw Ballard crumple to the ground during Thursday afternoon's practice.

"It was silence,'' he said. "Everybody just sort of gasped.

"You hope for the best, but you knew something wasn't right. He's a tough kid. To see him on the ground like that you knew something wasn't right.''

It wasn't the first time the Colts have lost a player for the season with an injury suffered during non-contact practice drills. Twice, cornerback Marlin Jackson saw his season end prematurely at practice.

Ballard was going about the business of running plays with the No. 1 offense. In a non-contact drill, he planted his right knee to make a cut. It gave and he went down.

"Freak accident,'' coach Chuck Pagano said, shaking his head.

"It's tough, but you also know that's the nature of the game,'' linebacker Robert Mathis said. "(It can be) one play, whether it's a game or practice.''

Ballard's loss is a major blow. He led the team in rushing as a rookie with 814 yards and had a team-best 63 yards in the season-opening win against the Oakland Raiders. Ballard was a powerful between-the-tackles runner and a willing blocker in pass protection.

"My heart goes out to Vick, man,'' offered Ahmad Bradshaw. "Our plan was to be that one-two punch.''

Now, the one-two punch consists of Bradshaw and Brown, starting with Sunday against the Miami Dolphins at Lucas Oil Stadium.

Bradshaw is the sixth-leading rusher in New York Giants history, but he missed all four preseason games while fully recovering from January surgery on his right foot. He rushed seven times for 26 yards against the Raiders.

"I'm ready,'' Bradshaw said. "I'm willing to go anytime.''

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Ditto, Brown. The 2009 first-round draft pick has shown flashes, but his availability and effectiveness has been limited by injuries. He finished the 2012 season on injured reserve with an ankle injury.

Brown has rushed for 1,840 yards and 11 touchdowns in 51 games. He's had two of the Colts' four 100-yard rushing games since 2010, the latest a career-best 161 yards on 16 attempts against Tennessee on Dec. 18, 2011.

Ballard briefly was at his locker Friday afternoon but declined comment.

In a nearby cubicle, veteran receiver Reggie Wayne empathized with his injured teammate. Wayne suffered a similar injury at the University of Miami.

"I had a little talk with him. I told him, 'I've had the injury before. Keep your head up. We'll fight for you,' '' Wayne said. "It's just a tough injury, but we all know this is part of this business. Hopefully he can have a successful surgery and a great rehab.

"I think we have the right components in place in all the right places to bounce back from this.''